Wednesday, April 27, 2011

First shot at the thermocouples

I sort of came up with the schematic. Eagle got a little creative with the symbol names, but I am not sending this out to have the board fabricated, so it probably isn't critical.

The upper clump is the CHT thermocouples, the lower clump is the EGT thermocouples. Each group with their own temperature compensating circuit. I didn't put any values on this. It is mostly an expanded version of the schematic in the Linear LT1014 data sheet. That datasheet has some interesting resistor values (IE 199K) I'll play with things a little bit, to see how accurate I get it with standard components. I suspect, it'll be good enough.

The datasheet is shooting for 10mV / degree C, I can use math to change to 9.82mV / degree C or even 10.28mV.

I've ordered the bluetooth shield, and expect it before the weekend. I am kicking myself, since I ordered from seed studio, and they  have prototype shields (cheap too!) that I didn't order one of those at the same time.

Again, any feedback is more than welcome.

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